1. Field of the Invention
The present invention relates generally to a fine inductor and more particularly to a fine inductor having a 3-dimensional coil structure on a surface of a semiconductor, wherein the inside of the coil is hollow, and also relates to a method for producing such a fine inductor.
2. Description of Related Art
Generally, a fine inductors having a micrometer size is used for a low and high frequency transmitter and receiver as passive components which are necessary for realizing a transmitting and receiving circuit for a specified electromagnetic wave in a radio communication integrated circuit.
When the inductor is integrated on the integrated circuit, however, since processing of 3-dimensional coil structure is difficult, a spiral structure having a coil structure which is partially planar is mainly used. The inductor having the plane coil structure has large design areas, has large parasitic capacitances which are generated from bottom portions of metal wirings structurally, and requires spaces between the metal wirings and inductor to avoid electrostatic induction in portions over which the metal wirings are crossed.
Further, method is proposed for realizing vertical coil shape by piling metal layers and insulating layers on the substrate in a multi-layer structure, but its manufacturing method is complex and because the insulating layers are filled between the coils, it has large parasitic capacitances and large contact resistances in wiring, thereby providing large resistance of inductor itself.